Rheumatoid arthritis
Definition
A chronic, systemic, autoimmune, inflammatory disorder, prinicipally affecting the joints.
Epidemiology
Affects around 1% of the world population. Incidence peaks around 40-50 years old and is three times commoner in women than men.
Pathophysiology
It is an autoimmune condition, the precise causes of which are poorly understood but results in inflammation of the synovium. However, it affects loads of organs, not just the joints. These include skin, heart, kidneys and lungs
Risk Factors
The only identifiable risk factor is smoking - other than that, nothing particularly specific
Clinical Features
These depend on which organ they are affecting. However, the joint problems are present in nigh on all cases.
Joints
Usually, the pattern of pain is described as a symmetrical polyarthritis. They become inflamed (swollen, red, painful and hot) and stiff. The prinicpal areas are affected are the small joints (IPJs and MCPs). The joints tend to get stiff in the morning or after any period of prolonged inactivity. As the disease progresses, loss of mobility occurs and the following deformities may occur:
- ulnar deviation
- "swan-neck" deformity - PIPJ extension, DIPJ flexion
- Boutonniere deformity - knuckle constantly bent towards palm
- Z-deformity - the thumb goes into a Z-shape (a medical term that is actually helpful for once)
Generalised features
As this is a systemic disease, it regularly causes non-specific symptoms such as: low-grade fever, malaise and weight loss
Other organs
DON'T learn all of these in detail. This is just to point out the RA is systemic, not just a joint problem. You should be aware that it affects basically everything.
- Skin
- rheumatoid nodules are important because they are practically diagnostic of the condition. They are fibrous nodules with a necrosed centred
- vasculitis
- lungs - look for fibrosis, pleural effusions, lung nodules (particularly with coal dust)
- kidneys - deposition of proteins (amyloidosis) and immune-complexes
- liver - hepatomegaly (due to increased action of Kuppfer cells)
- blood - normocytic anaemia, neutropenia, splenomegaly in Felty's syndrome
- neurological - peripheral neuropathy, mononeuritis multiplex
- bone - osteoporosis
- lymph - lymphoma
- eyes - dryness leading to episcleritis or Sjogren's syndrome
- salivary glands - Sjogren's syndrome
Investigations
Bloods
- FBC - anaemia, neutropenia
- U+Es - kidney function
- LFTs - ↑alk phos (& Gamma-GT)
- ESR & CRP - are inflammatory markers which, CRP particularly, can be used as indicators of the effectiveness of treatments
- Rheumatoid factor - NOT diagnostic (not sensitive or specific) but a significant factor in diagnosis.
- Uric acid - excludes gout
- Urinalysis - haematuria or proteinuria may suggest connective tissue disease
- ANA - positive in SLE but also 30% of rheumatoid arthritis
Imaging
X-ray affected joints - soft tissue swelling, periarticular osteopenia, loss of joint space, erosions and deformity
Management
Pharmacological
The key to drug to setting up drug regimen is trying to get so-called "tight control". This means as low a dose as possible without desired side-effects but it also means early treatment i.e. as soon as the disease is diagnosed or worsens, treatment should become more intense.
There are a few different classes of drugs which are involved in the treatment of RA but the main class are the so-called "disease modifying antirheumatic drugs", otherwise known as:
DMARDs
These include methotrexate which is the first-line treatment of rheumatoid arthritis. There are a variety of tests that need to be done in order to monitor the potential side-effects of methotrexate. Sulfasalazine and gold injections are the next-line treatments. DMARDs reduce pain and swelling but are also shown to slow disease progression whereas many other drugs do not.
Other DMARDs have potential adverse side-effects which is why they are not used in the first instance and must be prescribed with care. DMARDs require 6 months to reach their full effectiveness but should have some effect after 3 months.
Other drugs
These include:
- NSAIDs (ibuprofen, diclofenac, naproxen) - these can reduce pain and inflammation but do no slow disease progression.
- COX-2 inhibitors (celecoxib, etoricoxib) - similar to NSAIDs but more expensive. Idiosyncratic side-effects so can used as an alternative
- Anti-TNF (infliximab, etanercept) - used in those who fail to respond to DMARDs
- Corticosteroids (prednisolone) - can be used for symptom control, often whilst waiting for DMARDs to take effect.
Non-pharmacological
Basically occupational therapy and physiotherapy are the main ones. Often social workers are needed to help with problems at home at issues with benefits and such. Counselling can be helpful and RA can have a severed psychological effect.
Prognosis
The course of the disease varies from perons to person; some have a relapsing-remission course, others a progressive one. Life expectancy is reduced. 90% are clinically disabled within 20 years and 50% are unable to work after 10 years. The following are risk factors for poor progress:
- insidious onset
- male
- extra-articular manifestations (non-joint problems)
- functional disability after 1 year
- high rheumatoid factor
- Erosions on X-ray within 3 years